I'm not sure if it is possible but I think that it would be cool if we could adjust the size of the youtube videos like we can for images. Not so much to make them larger but smaller. With images we can include a size in the tag such as small or micro. Is that possible with youtube links? I'm thinking not.

The only images you can resize are the ones hosted by BGG. I'm pretty sure it's not possible with YouTube videos. All the BGG code does is embed the video in a post, but the video itself is still hosted by Youtube and is only tweakable by them.

BGG used to allow the start parameter that would make the video start at a preselected cue point. Then about a couple of months ago, that stopped working. Not sure if other parameters worked and then stopped working too. You can try experimenting in the Test forum.

I don't think it was BGG so much as it was YouTube. YouTube has implemented several changes over the past year or so. It wouldn't surprise me if those changes broke some of the functions coded into BGG.